1. Field of the Invention
The present invention relates to electrical connectors and, in particular, to contacts environmentally sealed within such connectors for use with underwater streamers.
2. Description of the Prior Art
Environmental sealing of electrical contacts within their insulated connector bodies sometimes raise special problems when applied to specific environments. In particular, streamers used in underwater towed cables and the like give rise to special pressure and sealing problems. Such streamers or underwater cables comprise a wire bundle enclosed in a fluid-filled jacket and terminated by electrical connectors and contacts therein coupled to individual wires. Sea pressure exerts large forces on the jacket and the enclosed fluid and, unless the contacts were properly sealed in their bores of the connector body, fluid would be forced to the front of the connector.
Potting, tight packing seals and hermetic contacts have been used to effect the proper fluid and pressure-type sealing required in such systems, but without the absence of problems. The major disadvantage to potting is that once the contacts are potted in the connector, it is not possible to repair or replace them and the malfunctioning connector must then be discarded. The same problem results from the use of hermetic contacts, which are also not removable from the connector body. Packing seals, while overcoming the repair disadvantage of potting, require great pressure to tighten the seals securely in place to withstand leakage. Through use or improperly applied pressure, the quality of their sealing will deteriorate and the fluid within the streamer will then leak past the contacts.
A further system which overcomes the disadvantages of potting and pressure seals is disclosed in U.S. Pat. Nos. 3,792,416 and 4,133,593, respectively entitled, "System, Method and Seal for Pressure-Sensitive Wire and Interface Sealing of Electrical Connector Assemblies and Associated Contacts" and "Pressure Sensitive Seal for Wire and Interface Sealing of Individual Contacts in and between Electrical Connectors," both by Norbert L. Moulin, one of the co-inventors herein. Both describe seals for, and sealing of, electrical contacts from the environment external to the interior of a connector regardless of changing pressure conditions. One of the seals disclosed therein, a pressure-sensitive wire seal at the rear of each connector, includes a tubular portion jacketed in sealing contact on the conductor insulation, a cup-shaped flange opening toward the rear of the connector, a wiper land inwardly disposed of the cup-shaped flange, and an interlocking engagement between the seal and the wire-receiving end of the contact. Because the cup-shaped flange faces rearwardly, sealing is proportionately enhanced when the pressure external to the bore, in which the contact is sealed, increases as a result of increased sealing pressure exerted against the cup-shaped flange.
In both patents, the pressure-sensitive wire seal is positioned on the wire-receiving end of the contact. Such wire-receiving ends conventionally include holes or perforations which provide an access for crimping or soldering and inspection of the wire which is soldered or crimped within the contact end. Placement of a wire seal behind the inspection hole in a fluid-filled streamer or underwater cable gives rise to a special, but serious problem. Specifically, due to the pressures exerted on the fluid in the streamer jacket, the fluid is forced along the wires or cables and enters the wire-receiving end of the contact. Thence, it moves through the inspection hole to the front, contact mating end of the contact. Thus, the fluid by-passes the pressure-sensitive wire seal.